server_supports(): parse feature list more carefully

We have been carefully choosing feature names used in the protocol
extensions so that the vocabulary does not contain a word that is a
substring of another word, so it is not a real problem, but we have
recently added "quiet" feature word, which would mean we cannot later
add some other word with "quiet" (e.g. "quiet-push"), which is awkward.

Let's make sure that we can eventually be able to do so by teaching the
clients and servers that feature words consist of non whitespace
letters. This parser also allows us to later add features with parameters
e.g. "feature=1.5" (parameter values need to be quoted for whitespaces,
but we will worry about the detauls when we do introduce them).

Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Clemens Buchacher <drizzd@aon.at>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/receive-pack.c

@@ -731,9 +731,10 @@ static struct command *read_head_info(void)
 		refname = line + 82;
 		reflen = strlen(refname);
 		if (reflen + 82 < len) {
-			if (strstr(refname + reflen + 1, "report-status"))
+			const char *feature_list = refname + reflen + 1;
+			if (parse_feature_request(feature_list, "report-status"))
 				report_status = 1;
-			if (strstr(refname + reflen + 1, "side-band-64k"))
+			if (parse_feature_request(feature_list, "side-band-64k"))
 				use_sideband = LARGE_PACKET_MAX;
 		}
 		cmd = xcalloc(1, sizeof(struct command) + len - 80);

cache.h

@@ -1037,6 +1037,7 @@ struct extra_have_objects {
 };
 extern struct ref **get_remote_heads(int in, struct ref **list, unsigned int flags, struct extra_have_objects *);
 extern int server_supports(const char *feature);
+extern const char *parse_feature_request(const char *features, const char *feature);
 
 extern struct packed_git *parse_pack_index(unsigned char *sha1, const char *idx_path);
 

connect.c

@@ -101,8 +101,27 @@ struct ref **get_remote_heads(int in, struct ref **list,
 
 int server_supports(const char *feature)
 {
-	return server_capabilities &&
-		strstr(server_capabilities, feature) != NULL;
+	return !!parse_feature_request(server_capabilities, feature);
+}
+
+const char *parse_feature_request(const char *feature_list, const char *feature)
+{
+	int len;
+
+	if (!feature_list)
+		return NULL;
+
+	len = strlen(feature);
+	while (*feature_list) {
+		const char *found = strstr(feature_list, feature);
+		if (!found)
+			return NULL;
+		if ((feature_list == found || isspace(found[-1])) &&
+		    (!found[len] || isspace(found[len]) || found[len] == '='))
+			return found;
+		feature_list = found + 1;
+	}
+	return NULL;
 }
 
 enum protocol {

upload-pack.c

@@ -585,6 +585,7 @@ static void receive_needs(void)
 		write_str_in_full(debug_fd, "#S\n");
 	for (;;) {
 		struct object *o;
+		const char *features;
 		unsigned char sha1_buf[20];
 		len = packet_read_line(0, line, sizeof(line));
 		reset_timeout();
@@ -616,23 +617,26 @@ static void receive_needs(void)
 		    get_sha1_hex(line+5, sha1_buf))
 			die("git upload-pack: protocol error, "
 			    "expected to get sha, not '%s'", line);
-		if (strstr(line+45, "multi_ack_detailed"))
+
+		features = line + 45;
+
+		if (parse_feature_request(features, "multi_ack_detailed"))
 			multi_ack = 2;
-		else if (strstr(line+45, "multi_ack"))
+		else if (parse_feature_request(features, "multi_ack"))
 			multi_ack = 1;
-		if (strstr(line+45, "no-done"))
+		if (parse_feature_request(features, "no-done"))
 			no_done = 1;
-		if (strstr(line+45, "thin-pack"))
+		if (parse_feature_request(features, "thin-pack"))
 			use_thin_pack = 1;
-		if (strstr(line+45, "ofs-delta"))
+		if (parse_feature_request(features, "ofs-delta"))
 			use_ofs_delta = 1;
-		if (strstr(line+45, "side-band-64k"))
+		if (parse_feature_request(features, "side-band-64k"))
 			use_sideband = LARGE_PACKET_MAX;
-		else if (strstr(line+45, "side-band"))
+		else if (parse_feature_request(features, "side-band"))
 			use_sideband = DEFAULT_PACKET_MAX;
-		if (strstr(line+45, "no-progress"))
+		if (parse_feature_request(features, "no-progress"))
 			no_progress = 1;
-		if (strstr(line+45, "include-tag"))
+		if (parse_feature_request(features, "include-tag"))
 			use_include_tag = 1;
 
 		o = lookup_object(sha1_buf);